Collier County Sheriff's Office deputies are investigating a homicide after a woman was found dead inside a residence in Immokalee on Thursday.

Video by Elysa Batista

Collier County Sheriff's Office deputies are investigating a homicide after a woman was found dead inside a residence in Immokalee on Thursday.

Video by Elysa Batista

Francisco Demetrio Carrillo

IMMOKALEE - The brother-in-law of Iris Lopez Contreras confessed to killing the Immokalee woman on Jan. 28, according to documents filed with the Collier County Clerk's Office on Monday.

Francisco Demetrio Carrillo, 36, was arrested Friday and charged with second-degree murder in connection with the death of 29-year-old Contreras.

He is the brother of the victim's husband, Marco Tulio Carrillo, and also lived at the victim's home in the 100 block of N. 7th St. in Immokalee.

At the time of his arrest he was in the Collier County jail in Naples on a warrant out of Lee County.

According to the arrest report released Friday, Collier deputies responded to the scene after the Contreras' 6-year-old son discovered her bloodied body when he arrived home from school.

The detectives determined Contreras died of multiple wounds to the head with a blunt object, the report said.

During the investigation, reports said detectives learned through friends and family that Francisco Demetrio Carrillo, Contreras' brother-in-law, may have been involved in her death.

A break in the case came Wednesday, when detectives got a call saying that Carrillo -- going by his brother Marcos' name -- was already in the jail on a warrant out of Lee County.

In a tape-recorded interview conducted by a Collier County sheriff's detective on Wednesday, documents show that Carrillo admitted having an argument with Contreras "that escalated into a physical confrontation in which he intentionally struck her multiple times."

Reports said Carrillo provided specific details of the scene, which included the victim's injuries, which would only be known by the person who committed the crime.

"The injuries described by Carrillo were determined by the Medical Examiner to have been directly responsible for the death of Contreras," the court document showed.